Ionization, dissociation and desorption of pyrimidine ice due to X-ray interaction

The photoionization and the photodissociation of pyrimidine in condensed phase due to soft X-ray interaction were experimentally investigated. The measurements were performed at the Brazilian Synchrotron Light Source (LNLS), operated in the single-bunch mode, employing X-ray photons at energies around the C1s (288 eV) and N1s (400 eV) resonances. Mass spectra of ionic fragments desorbed from pyrimidine ice were obtained using the time-of-flight mass spectrometry (TOF-MS). The photodesorption yields (ions photons−1) and ion yields (cm−3 s−1) were determined, providing data to astrochemistry models.